1) Field of the Invention
The field of this invention relates to sound systems and specifically to a sound system that is installed within a home or business where the sound system operates multiple sets of loudspeakers which are located in different rooms of the home or business.
2) Description of the Prior Art
There is a trend of people longing to have music enjoyed in multiple rooms of their home or place of business. The conventional way to install such a stereo system or a radio within a home or business is to have one sound source (receiver, amplifier, CD player, tape deck, and so forth) in a central location of a house or place of business. Wires are then run to different sets of loudspeakers located within each room. A problem then occurs that the amplifier from the sound source cannot safely power all of the loudspeakers simultaneously unless such are connected in a certain pattern which changes depending upon the number of loudspeakers used. A manual loudspeaker selector can solve the problem with this being located at the central source which provides on and off selection for the loudspeakers within the rooms desired. For example, if the user wants the bedroom in an off position but the family room speakers on, such can be selected at the central source. The drawback to this type of an arrangement is that the selector is located at the central equipment location thus forcing the user to leave the room in which the operation or deactivation of the loudspeakers is desired.
Another problem is that if the loudspeakers are too loud in one room and not loud enough in another room, there is no way to change the volume levels in each room independently. A product exists similar to a manual speaker selector with this product again being located at the central location. This product adds volume control for each set of loudspeakers. This, too, has a disadvantage in that the user needs to make the change at the central location to adjust the volume of a particular set of speakers within a particular room. Also, the user has to speculate as to exactly what level the speakers are to be turned on to in a particular room since the user is not located within that room. Frequently, a user will turn on the speakers thinking that the desired level has been obtained. When the user then goes into the specific room the user now knows that the loudspeakers are either too loud or they are too low which requires the user to go back and readjust the volume at the central location.
The most commonly used method an apparatus to solve the volume problem with different sets of loudspeakers within different rooms is installation of volume controls within each room which are wired in line with the loudspeaker wires that run into that room. Now, volume control is independent, but there is no way to turn on the equipment, choose between sound sources, or make changes to the sound source (such as a CD player, radio station or tape player) without returning to the central sound source location. There are ways to solve this problem of controls within each room. However, these ways are exceedingly expensive and also require a significant amount of added equipment plus the running of additional wiring to each room from the central source to provide the control functions.
The structure of the present invention relates to a circuit installed between remote sets of loudspeakers and a central sound source. This circuit constantly monitors the position of the volume control of each set of loudspeakers in each room, and when a change is noted, it activates appropriate switches and safely turns on the appropriate set of loudspeakers. The primary advantage of the present invention is that it uses existing wiring. Only the equipment at the central source and at the loudspeaker sets needs to change. A track or station selection can be added with only equipment changes at the central source and the remote sets of loudspeakers not requiring the addition of any wiring. The added circuit utilizes a high frequency (out of the range of human hearing) sense signal that is added to the audio that feeds the volume control of each loudspeaker set. Using a sense resistor to create a voltage divider with the volume control, the amplitude of the sense signal can be measured and from that deduce the position of the volume control for each particular set of loudspeakers. High pass and low pass filter circuits are used to isolate the audio amplifier and the sense signal generator from each other. The low pass filter circuit is designed to be able to handle the same power level as the volume control from the central sound source. There is utilized a peak detector circuit which will convert the high frequency sense signal to a DC signal. This DC signal can be amplified. A processor will determine if a level change has occurred which indicates the volume control for a particular set of loudspeakers has been moved. By measuring the level, we can determine the switch position relative to a maximum and a minimum position. This determining of the switch position can be accomplished by digital or analog means. A digital processor has the advantage of easy calibrating the levels so the loads of different sets of loudspeakers can be compensated accordingly. A digital processor can also cause activation or deactivation of the audio to the particular set of loudspeakers.